Czech VZLUSAT-1 reports from the orbit

VZLUSAT-1  (illustrative photo)

On June 23, 2017, the two-kilogram Czech nanosatellite VZLUSAT-1 was transported to the Earth's orbit using the PSLV-C38 rocket launched from Indian space spaceport at Sri Charikota Island. Now the nanosatellite circulates on a polar track at an altitude of 505 km with an orbital velocity of 7610 m / s.

The VZLUSAT-1 nanosatellite was developed on the basis of a standardized CubeSat 2U platform (20x10x10cm) in the Czech Aerospace Research Centre (VZLU) in cooperation with Czech companies and universities. The satellite carries three experiments on board. Miniaturized X-ray telescope developed by the joint efforts of Rigaku Innovative Technologies Europe, HVM PLASMA and the Institute of Technical and Experimental Physics of the Czech Technical University in Prague. A new type of composite material for space radiation shielding has been developed by the company 5M together with the TTS company, special sensors were provided by Innovative Sensor Technology. The FIPEX instrument for measuring oxygen concentration in the thermosphere was provided in the framework of the international mission QB50, which is based on the consistency of nanosatellites from different countries around the world. In addition to the own resources of the co-operating partners, the Technology Agency of the Czech Republic participated in the financing of the development and launching of the satellite within the framework of the Alfa program (projects TA03011329 and TA04011295), and the Ministry of Industry and Trade through the institutional funding of VZLU.

The control of the satellite by a terrestrial radio station is provided by the Department of Applied Electronics and Telecommunications of the University of West Bohemia in Pilsen (UWB). The UWB Ground Station captured the satellite radio signal at the first flypast over the Czechia. Since then, a team of scientists and engineers, led by Dr Vladimír Daniel from VZLU, are in regular contact with the satellite. These days, nanosatellite is put into full operation and the individual subsystems are gradually started up and their function checked.

The current two-line element (TLE) is regularly updated on this link:https://www.celestrak.com/NORAD/elements/tle-new.txt 

Communication system: The satellite broadcasts at a frequency of 437.240 MHz using a radio beacon. The signal is transmitted in the Morse alphabet with the text “VZLUSAT1” with a repetition of 30s throughout the Earth's round.

During the flight over the Czech Republic, the UWB provides regular data communication with the satellite. At this point, the radios are no longer broadcast, but two-way data communications at higher transmission speeds is running. At present, the ground control centre has a minor problem with the set-up of the maximum data transfer rate due to interference arising from some of the other 30 satellites that were launched together with VZLUSAT-1 and which are now practically on the same orbit. In the next period it is expected that the tracks of the individual satellites will be more distant and thus better data transmission will be possible. However, the current state is sufficient for all communication and commencement of individual planned measurements.

The power system works, the satellites continuously recharge the batteries. All solar panels are tilted and supply the required battery power. The batteries operate in an optimum temperature range of 10 ° C to 20 ° C.

Satellite rotation: The satellite magnetometer data shows that satellites are currently rotating at low speeds with 120s around the Z axis and 160s around Y and 480s around the X axis. In the coming days, commands will be sent to orbit for active rotation stopping and full 3D satellite stabilization. The satellite orientation and stabilization system was developed in the VZLU and is based on the use of torque coils of so-called magnetorquers. It is a system of three electromagnetic field coils that, thanks to interaction with the Earth's magnetic field, produce the desired torque.

On board computer: On-Board Computer OBC function is normal. What makes the research team most concerned is repeated locking of the main bus with one of the subsystems. The automatic restraint system then restarts the satellite after ten minutes of inactivity. The problem is probably caused by cyclical temperature changes. Blocking the master bus has an effect on saving data from some experiments. Experiments connected directly to the OBC are unfortunately not burdened by this problem.

Temperatures: There are 35 temperature sensors on the satellite that are located on most of the outer shell of the satellite and for monitoring the internal temperature of all subsystems. Meanwhile, regular measurements from the basic satellite systems, such as the power system, the radio, and the on board computer, are available. Recording from several angles shows the difference in temperature on the individual parts of the satellite. From the first measurements, it is clear that at night-time when the temperature of the on-board computer is around + 10 ° C, at the ends of the tilting solar panels -25 ° C. A detailed measurement of all space on the satellite will only begin.

X-ray Telescope: Data from the first X-ray telescope launch has already been sent to Earth. Measurements indicate that the system behaves as expected, the binocular parameters such as exposure time, data storage type, etc. can be set. For the time being, basic dosimetric measurement dosimetric measurements of space radiation without the optic are displayed. Tilting the telescope optics and observing the sun is planned early in the fall of this year.

New radiation shielding: A system for measuring the quality of composite radiation shielding has been activated. The first data received are very promising, and they are currently being processed.

Starting FIPEX to measure oxygen concentration in the atmosphere is scheduled for early August 2017.

The lifetime of the satellite is estimated at two years. During this time it will be possible to carry out a series of planned experiments and measurements in space. The scientific team will inform the public about the state of the VZLUSAT-1 mission in the news on www.vzlusat1.cz.